The present invention generally relates to an input-integrated display apparatus of a structure in which a coordinate input designating part is integrated with a display screen. More particularly, the invention concerns an input-output coordinate transforming method and apparatus for transforming input coordinates to output coordinates in such a manner that a point inputted by an operator through the input coordinate designating means is caused to coincide with, when viewed by the operator, an output point displayed on the screen in response to the input point.
Heretofore, an instrument referred to as a planar tablet or mouse is made use of as the means for designating a point to be displayed on a screen of a display apparatus. The tablet on which the point to be displayed is designated by operator is provided separately from a display panel. Operator designates a point on the tablet while observing the cursor displayed on the display screen or diverting his eyes from the display screen. This process involves no problem to be mentioned in the case of man-machine communication where only a single point is to be inputted. However, in case a line, i.e. a continuous sequence of points is to be inputted, the operator is compelled to move his hand while holding a stylus pen, followed by observation of a cursor displayed on the display screen for identifying displacement of the cursor on the display screen and subsequently by the movement of the pen, so to say, in a feedback loop. Such procedure in general reguires an increased number of operations, e.g. visual detection or confirmation of the result of the displacement of the operator's hand, which is followed by the visual verification, as in the case of manual drawing of a line. In this case, the hitherto known display apparatus is inconvenient for use. As attempts for overcoming the inconveniences mentioned above, proposals have been made as disclosed in Japanese Patent Laid-Open Publications Nos. 105332/75 and 72282/80. According to the teaching disclosed in Japanese Patent Laid-Open Publication No. 105332/75, a transparent manipulation plate is provided on an image displaying screen of a CRT display apparatus so that operator can observe the image on the display screen of the CRT through the transparent plate. When the operator designates a position on the transparent manipulation plate with a writing pen while observing the image on the display screen, the positional information of the designated point is supplied to the CRT to be displayed on the screen at a point designated by the positional information. On the other hand, in the case of the display apparatus disclosed in Japanese Patent Laid-Open Publication No. 72282/80, an input sheet constituted by a plurality of transparent resistance plates is disposed on a display screen of the display apparatus. When an electric pen held by an operator and driven by an alternating current is brought into contact with the input sheet, the alternating current flows into the resistance plates from the pen or stylus, whereby the alternating currents derived through the resistance plates arrayed in X- and Y-directions of orthogonal X-Y coordinate system are supplied to a stylus position detecting circuit, which in turn produces a signal representative of the coordinates (x, y) of the position of the pen contacting the input sheet. This signal is supplied to the display apparatus to be displayed on the screen at the corresponding coordinate position. When the input coordinate designating means is to be combined integrally with the display screen, there arises however a problem that the input coordinate point designated on the input panel by the operator is deviated from the output coordinate point displayed on the display screen which coincides with the designated point in appearance when viewed by the operator due to thickness of the input panel of the input coordinate designating means, the curvature of the surface of the display screen and the thickness thereof. The deviation will vary significantly in dependence on the attitude or posture of the operator. There is no proposal as to the measures for preventing such deviation. More particularly, no proposals have been yet made as to the method of making the input coordinates coincide with the output coordinates so that the input coordinates of a point designated on the input panel by the operator corresponds to the output coordinates of the point displayed on the display screen which coincides with the designated point when viewed by the operator.